Carbohydrate and carbon metabolite accumulation responses in leaves of ozone tolerant and ozone susceptible spinach plants after acute ozone exposure

The objective of this study was to determine whether exposure of plants to ozone (O₃) increased the foliar levels of glucose, glucose sources, e.g., sucrose and starch, and glucose-6-phosphate (G6P), because in leaf cells, glucose is the precursor of the antioxidant, L-ascorbate, and glucose-6-phosphate is a source of NADPH needed to support antioxidant capacity. A further objective was to establish whether the response of increased levels of glucose, sucrose, starch and G6P in leaves could be correlated with a greater degree of plant tolerance to O₃. Four commercially available Spinacia oleracea varieties were screened for tolerance or susceptibility to detrimental effects of O₃ employing one 6.5 hour acute exposure to 25O nL O₃ L^-1 air during the light. One day after the termination of ozonation (29 d post emergence), leaves of the plants were monitored both for damage and for gas exchange characteristics. Cultivar Winter Bloomsdale (cv Winter) leaves were least damaged on a quantitative grading scale. The leaves of cv Nordic, the most susceptible, were approximately 2.5 times more damaged. Photosynthesis (Pn) rates in the ozonated mature leaves of cv Winter were 48.9% less, and in cv Nordic, 66.2% less than in comparable leaves of their non-ozonated controls. Stomatal conductance of leaves of ozonated plants was found not to be a factor in the lower Pn rates in the ozonated plants. At some time points in the light, leaves of ozonated cv Winter plants had significantly higher levels of glucose, sucrose, starch, G6P, G1P, pyruvate and malate than did leaves of ozonated cv Nordic plants. It was concluded that leaves of cv Winter displayed a higher tolerance to ozone mediated stress than those of cv Nordic, in part because they had higher levels of glucose and G6P that could be mobilized during diminished photosynthesis to generate antioxidants (e.g., ascorbate) and reductants (e.g., NADPH). Elevated levels of both pyruvate and malate in the leaves of ozonated cv Winter suggested an increased availability of respiratory substrates to support higher respiratory capacity needed for repair, growth, and maintenance.Abbreviations ADPG-PPiase ADPglucose pyrophosphorylase - ASC L-ascorbic acid - APX ascorbate peroxidase - Ce CO₂ concentration in air in the measuring cuvette during photosynthesis measurements - Ci CO₂ concentration in the leaf intercellular spaces during photosynthesis measurement - Chl chlorophyll - DHA dehydroascorbic acid - DHA reductase dehydroascorbate reductase - DHAP dihydroxyacetone phosphate - GAP glyceraldehyde-3-phosphate - Gluc glucose - GR glutathione reductase - G_sw stomatal conductance with units as mmol H₂O m^-2 s^-1 - GSSG oxidized glutathione - GSH reduced glutathione - G1P glucose-1-phosphate - G6P glucose-6-phosphate - G6P dehydrogenase glucose-6-phosphate dehydrogenase - 6PG 6-phosphogluconate - 6PG dehydrogenase 6-phosphogluconate dehydrogenase - F6P fructose-6-phosphate - FBP fructose-1,6-bisphosphate - MAL malate - MDHA reductase monodehydroascorbate reductase - PE post-emergence - PEP phosphoenolpyruvate - PGA 3-phosphoglycerate - Pi orthophosphate - PYR pyruvate - Pn net CO₂ photoas-similation in leaves - PPFD photosynthetic photon flux density with units of mol photons m^-2 s^-1 - PPRC pentose phosphate reductive cycle - RuBP ribulose-1,5-bisphosphate - rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - SLW specific leaf weight - TCA cycle tricarboxylic acid cycle - Triose-P DHAP+GAP     

Effect of maximal arm exercise on skin blood flux in the paralyzed lower limbs in persons with spinal cord injury

The purpose of the present study was to examine the effect of maximal arm exercise on the skin blood circulation of the paralyzed lower limbs in persons with spinal cord injury (PSCI). Eight male PSCI with complete lesions located between T3 and L1 performed graded maximal arm-cranking exercise (MACE) to exhaustion. The skin blood flux at the thigh (SBFT) and that at the calf (SBFC) were monitored using laser-Doppler flowmeter at rest and for 15 s immediately after the MACE. The subject's mean peak oxygen uptake and peak heart rate was 1.41 ± 0.22 1·min⁻¹ and 171.6 ± 19.2 beats·min⁻¹, respectively. No PSCI showed any increase in either SBFT or SBFC after the MACE, when compared with the values at rest. These results suggest that the blood circulation of the skin in the paralyzed lower limbs in PSCI is unaffected by the MACE.     

Hydraulic sorting of microbiota in calciturbidites— A dinantian case study from the rheinische schiefergebirge,Germany

Summary A calciturbidite bed from the lower part of the Kieselkalk Formation (late cd II) at Wallau, eastern Rheinisches Schiefergebirge, displays ideal grading of reworked calcareous shallow-water microbiota, ranging from plurimillimetric agglutinated foraminifers and fragments of calcareous algae (Koninckopora sp.) to plurimicronic calcispheres, radiolarians and sponge spicules. Microbiota derived from all levels of the platform. Correspondingly, several carbonate microfacies types could be discerned. The early diagenetic micrite base of the turbidite preserved the anoxic basinal facies. The turbidite bed belongs to Foraminiferal Zone 15 (V3bα), theAlbaillella cartalla Zone (radiolarian chronology), and is the Lower and part of the Uppertexanus Zone (standard conodont zonation). From the few published data on foraminifers, the Kieselkalk is thought to range from Mid Viséan V2b to Late Viséan V3b gamma.     

Impairment of raw 264.7 macrophage function by antiarrhythmic drugs

The effect of the antiarrhythmic drugs lidocaine, quinidine and procainamide on macrophage function was investigated in RAW 264.7 mouse monocytic macrophage cell. Cells stimulated by either zymosan or phorbol ester were found to generate both superoxide (O ₂ ^– ) and H₂O₂. The production of O₂ was detected as superoxide dismutase inhibitable ferricytochrome c reduction. H₂O₂ production was monitored in both chemical and flow cytometric fluorescent assays. Although all three drugs inhibited both O₂ and H₂O₂ release in a dose dependent manner, only quinidine was found to have significant inhibitory effects. The amounts of quinidine required to cause a 50% inhibition in O₂ production in zymosan and phorbol ester stimulated cells were found to be 250 M and 300 M, respectively and the amounts required to cause one-half optimum levels of H₂O₂ production in these cells were found to be 50 M and 100 M, respectively. The effect of these drugs on O₂ producing NADPH oxidase was investigated and only procainamide was found to have a significant effect (p<0.001) in inhibiting the oxidase activity. Lidocaine and quinidine had no significant effect on the activation of the respiratory burst oxidase. A sensitive and convenient differential phagocytosis assay was devised on the basis of number of particles engulfed by individual phagocytes using flow cytometric techniques. It appears to be remarkably free of interference and was applied to investigate the role of antiarrhythmic drugs on the phagocytosis of fluorescent latex beads. All three antiarrhythmic drugs inhibited phagocytosis of latex beads in a dose dependent manner irrespective of the number of particles phagocitized by the cells. The results of these studies do not conclusively establish a mechanism of action of these drugs on the generation of O₂ and H₂O₂ by stimulated macrophages; nevertheless, it is interesting that all three drugs inhibited the phagocytic activity.     

Energy metabolism of Chironomus anthracinus (Diptera: Chironomidae) from the profundal zone of Lake Esrom,Denmark, as a function of body size,temperature and oxygen concentration

The profundal zone of Lake Esrom, Denmark has a dense population of Chironomus anthracinus, which survives 2–4 months of oxygen depletion each summer during stratification. The metabolism of 3rd and 4th instar larvae was examined in regard to variation in biomass and temperature. Respiration at air saturation was described by a curvilinear multiple regression relating oxygen consumption to individual AFDW and temperature. At 10 °C and varying oxygen regimes the O₂ consumption and CO₂ production of 4th instar larvae were almost unaltered from saturation to about 3 mg O₂ l^–1, but decreased steeply below this level. The respiratory quotient increased from 0.82 at saturation to about 3.4 at oxygen concentrations near 0.5 mg O₂ l^–1. This implied a shift from aerobic to partially anaerobic metabolism. At 0.5 mg O₂ l^–1 the total energy production equalled 20% of the rate at saturation of which more than one third was accounted for by anaerobic degradation of glycogen. This corresponded to a daily loss of 12 µg mg AFDW^–1 or approximately 5% of the body reserves. At unchanged metabolic rate the glycogen store would last three weeks, but long term oxygen deficiency causes a further suppression of the energy metabolism in C. anthracinus.     

The barbs (Barbus spp.) of Lake Tana: a forgotten species flock?

Synopsis All living species occupy an ecological niche, and are positioned within a trophic hierarchy. Extinct organisms presumably held similar behavioral and coevolutionary characteristics in the past, and were susceptible to the same kinds of natural ecological pressures operating today. Paleoecological investigations are limited by the incompleteness of the fossil record, and particularly by a lack of behavioral data that are so fundamental to ecological studies of living communities and habitats. Opportunities to examine the coevolutionary structure of ancient communities from empirical data are extremely rare. One such opportunity is provided by the Lower Cretaceous Santana Formation of north-eastern Brazil, a series of richly fossiliferous strata approximately 110 million years old. Many fossil fishes from the Santana Formation contain identifiable prey, including decapod crustaceans and fishes. A trophic hierarchy of these organisms is reconstructed here, and their ecological relationships are discussed. Comparison is made with a similar fish fauna from the Upper Jurassic Solnhofen Limestone of Germany. Low-level, intermediate and high-level predators are identified in each fauna. Predator-prey relationships in the Santana fauna are strongly hierarchical, and are more focussed at the intermediate predator level than in Solnhofen. Comparison with a model of predator-prey relationships between fishes and benthic fauna of the Baltic Sea (which like the Araripe Basin represents a semi-enclosed environment) suggests that heavy predation on teleosts such asRhacolepis, occupying an intermediate trophic level, may have permitted benthic decapods to proliferate and exclude other benthic organisms. Less intense predation on fishes at the intermediate trophic level would allow their numbers to increase, thereby increasing the intensity of predation on the benthos at the base of the trophic hierarchy.     

Detection of Antibody-Coated Bacteria in Expectorated Sputum for Diagnosis of Lower Respiratory Infections

We evaluated antibody-coated bacteria (ACB) in expectorated sputum to discriminate contaminating or colonizing organisms from true pathogens. We examined 60 expectorated sputum samples from 51 patients with lower respiratory infections (chronic obstructive pulmonary disease 25, pneumonia 20, purulent tracheobronchitis 6). All samples were examined with quantitative culture and immunofluorescent demonstration of ACB. From the results of quantitative culture, we divided specimens into pathogen-isolated and pathogen-free samples. Among pathogen-isolated samples, in which we isolated accepted pathogenic organisms at ≥ 10⁷ colony-forming units per ml, 16 of 23 samples were ACB-positive (69.5%). In contrast, among pathogen-free samples, in which we isolated accepted pathogens at < 10⁷ colony forming units per ml or only upper respiratory flora, only 3 of 37 samples were ACB-positive (8.1%). The ACB-positive rate was significantly higher in pathogen-isolated than in pathogen-free samples (P < 0.001). Consequently, detecting ACB in expectorated sputum shows good potential as another criterion for distinguishing contaminating or colonizing organisms from true pathogens.     

Changes in dormancy of Sisymbrium officinaleseeds do not depend on changes in respiratory activity

Effects of dark incubation at different temperatures were studied on dormancy and respiratory activity of seeds of Sisymbrium officinale (L.) Scop. Because germination of this species absolutely depends on the simultaneous action of light and nitrate, changes in dormancy could be studied in darkness without the interference of early germination events. Upon the start of incubation rates of O₂ uptake and CO₂ release rose. This was followed by a gradual decrease until stable levels of O₂ uptake and CO₂ release were achieved. Seeds kept for prolonged periods at 24^°C, showed neither a change in germination capacity nor in rates of O₂ uptake and CO₂ release. Respiratory quotients were 0.55–0.7. The initial rise in O₂ uptake correlated with the rate of water uptake and with breaking of primary dormancy. However, the subsequent decline in O₂ uptake was not generally linked to induction of secondary dormancy. An increased O₂ uptake was not required during breaking of secondary dormancy. It is concluded that changes in dormancy are not generally related to changes in respiratory activity. However, germination strongly depends on respiration. The increase in O₂ uptake started well before radicle protrusion. A far red irradiation only reversed this increase when it was given before germination escaped from its red light antagonising action. The contribution of different respiratory pathways was followed during prolonged incubation at 24^°C in darkness. KCN at 1.5 mM was needed to inhibit the cytochrome pathway (CP) and benzohydroxamic acid (BHAM) at 30 mM to inhibit the alternative pathway (AP). These concentrations did not exert any side effects. Electron flow was predominantly via the CP, maximally 10% was via the AP. Flow through the CP declined during the first 6 days and residual respiration remained constant. Therefore, the contribution of residual respiration became relatively more important with prolonged incubation. KCN at concentrations that almost completely inhibited flow through the CP, did not dramatically reduce germination. BHAM already inhibited germination at concentrations that do not inhibit oxygen uptake.     

ANTIVIRAL ACTIVITY OF CULTURED BLUE-GREEN ALGAE (CYANOPHYTA)1

Lipophilic and hydrophilic extracts from approximately 600 strains of cultured cyanophytes, representing some 300 species, were examined for antiviral activity against three pathogenic viruses. Approximately 10% of the cultures produced substances that caused significant reduction in cytopathic effect normally associated with viral infection. The screening program identified the order Chroococcales as commonly producing antiviral agents.     

鄂东南地区下侏罗统武昌组的双壳类化石

湖北蒲圻车埠和大冶金山店下侏罗统武昌组的双壳类化石可划分为２个组合,武昌组中部Ｑｉｙａｎｇｉａ－Ａｐｓｅｕｄｏｃａｒｄｉｎｉａ组合和武昌组上部Ｈｕｂｅｒｉｃｏｎｃｈａ－Ｋｉｊａ（Ｗｕｃｈａｎｇｅｌｌａ）组合,前者时代为早侏罗世中晚期;后者暂归于早侏罗世最晚期。文中描述２新属１新亚属以及１５新种。